Fan blade



Aug. 9 1927. 1,638,129

K. L. PARKER FAN BLADE Filed Sept. 21, 1925 2 Sheets-Sheet 1 PatentedAug. 9, 1927.

UNITED STATES PATENT OFFICE.

KING L. PARKER, OF ST. LOUIS, MISSOURI, ASSIGN OR TO THE EMERSONELECTRIC MFG. (70., OF ST. LOUIS, MISSOURI, A CORPORATION OF MISSOURI.

FAN BLADE.

Application filed September 21, 1925. Serial No. 57,575.

This invention relates to improvements in fan blades, and consists inthe novel construction hereinafter disclosed.

An object of the invention is to provide 6 a fan blade having itssurface so curved that a substantial increase both in the dispersion andthrust of the air currents produced thereby will result.

7 A further object of the invention is to pro- 1 vide a fan blade havinga surface curvature whereby provision is made for increasing thedevelopment of the air currents by a greater degree of blade curvaturenear the axis of rotation resulting in a more nearly equal distributionof the air currents.

Additional advantages of the construction of the invention will bereadily understood from the following detailed description thereof takenin connection with the accompanying drawing in'which Fig. 1 is a planview of a blade attached to one arm of the spider.

Fig. 2 is a diagrammatic view illustratin the curvature of the fanblade, the curved segments being cross sections taken on theconstruction lines of Fig. 1.

Fig. 3 is a front view of one of the blades attached to an arm of thespider.

Fig. 4 is a front edge view of the same part.

In the embodiment of the invention illustrated in the drawing, the fanblade is shown as attached to a spider -1, it being understood that thespider has a plurality of arms,

and that it is carried by a rotating member 2, as is usual in electricfan construction.

The blades proper, only one of which. is illustrated in the drawing, areriveted to the respective arms of the spider by rivets 3, said 4 rivetsbeing in alinement. An extended line passing through the axis of therotating member and through the rivets, and extending to the outer edgeof the fan blade for the purpose of convenience of the description, willbe referred to as the rivet line of the fan blade, and is indicated inFig. 1 by the radial construction line.

By reference to Fig. 2, diagrammatically illustrating the curved surfaceof the blade, it will be noted that the portion of the fan blade to theleft of the rivet line has a substantially uniform downward deflectionhaving a relatively small degree of curvature. In other words, thatportion ofthe blade indicated by 4 on the drawing is substantially fiatwith a slight downward deflection from the rivet line. This area of theblade is on the side in the direction of rotation of the fan, and themarginal edge-of the area is the leading edge of the blade when inoperation.

That portion of the blade lying to the right of the rivet line andbounded on its outer extremities substantially by the construction linewith the numeral 4 above it, and indicated in the drawing by thereference numeral 5, has a relatively sharp degree of curvature from therivet line, the maximum degree of curvature lying substantially betweenthe construction lines 2 and 3 at the marginal edge of the fan. Thisarea of the fan blade, inasmuch as it is closer to the axis U ofrotation, has a reduced'circumferential speed as compared with the outerextremity of the fan blade. The upwardly turned curved surface 5, havinga greater degree of curvature, tends to compensate for the reducedcircumferential speed of the blade within this area. The result is thatby the greater curvature of the fan blade an increased amount of aircurrent production results as compared with the volume of the aircurrents produced near the outer extremity of the blade as a directresult of the curvature of the blade.

That portion of the blade lying to the right of the rivet line andbeyond the construction line 4, and indicated onthe drawing by thenumeral 6, has a less degree of curvature substantially graduatedoutwardly in proportion to the distance from the axis of rotation. Thisis apparent from the diagram of Fig. 2. The result is'that as thecircumferential speed of the area of the blade is increased the degreeof curvature is complementarily reduced. This further tends to equalizethe thrust of the air current produced by the revolving blade whenutilized in fan construction.

The marginal contour of the blade is not essential, but the inventionconsists in so proportioning the surface contour to the circumferentialspeed of the blade in operation as to result in equalized and uniformthrusts of air currents produced throughout the radial length of theblade. Practical use of the invention has demonstrated a verysubstantial increase both in the thrust and I edge of the fan blade,

dispersion of air currents PIOQUCBd. by afan equipped with the bladesembodying the invention. 7

A limited departure from the exact curvature shown is permissible, butany substantial variation reduces to an appreciable degree the efiectiveresults of the blade construction, and the structure of the inventionmay be modified to some degree without departure from the spirit andscope thereof.

What I claim and desire to secure by Letters Patent is 1. A fan bladecomprising an area downwardly deflected from a plane of a median line,said area terminating in the advanced an area adjacent to the inner edgeof the blade having a relatively sharp upward curvature at its marginaledge, and an area lying adjacent to said first named areashaving acurvature gradually reduced in degree proportionally to the distancefrom the axis of rotation.

2. A fan blade having a curved surface, the advanced area of which isdownwardly deflected and the trailing area of which is upwardly curved,having the maximum degree of curvature adjacent to the axis of rotationand having a gradually, decreasing degree of curvature toward the outermarginal edge of the blade.

- KING L. PARKER.

